G1 unlockable skins for Optimus Prime, Starscream, and Jazz.
     Enter  these  codes  with  the  D-pad  during  any  one  of  that
character's missions:

Cheat code:                                 Effect:
down, down, up, up, right, right, right     Optimus Prime G1 skin
right, down, left, left, down, up, up       Starscream G1 skin
left, up, down, down, left, up, right       Jazz G1 skin 
R L R L R L R                               No vehicle's running 
                                            on the street 
                                            and no tank's/cop's attack
R U U D R L L                               Unlocks bonus Cybertron 
                                            Autobot and Cybertron 
                                            Decepticon missions